This invention relates in general to systems operated by fluids under pressure and, more particularly, to a hydropneumatic system particularly suited for operation of a hydraulic truck trailer landing gear.
The present invention constitutes an improvement over the type of hydropneumatic landing gear systems disclosed in U.S. Pat. Nos. 3,177,664 and 3,447,319, each entitled Hydropneumatic System and in the name of R. L. Konkle.
In both of said patents, air is introduced into landing gear leg assemblies of the systems. It has been found that moisture entrained in the air can cause corrosion within the landing gear assemblies which may result in sticking, uneven operation, failure of the legs to extend or retract properly, and malfunctioning of components within the legs. Moreover, under some circumstances, high usage of air for operation of these known systems may result from actuating an air-hydraulic booster pump of said systems. Such usage could, under extreme circumstances, exhaust the air supply of a tractor-trailer, particularly if the tractor engine is not operating whereby its air compressor is not continually replenishing the air consumed by operation of the hydropneumatic system.
It is an object of the present invention to provide a system wherein a liquid, such as hydraulic oil, may be motivated by a pressurized gas, such as air.
It is a further object of the present invention to provide a system for operating landing gear of truck trailers in tractor-trailer combinations, which system is operative in response to motivating air pressure obtained from the air brake system of the tractor.
It is another object of the present invention to provide a tractor-trailer landing gear actuating system of the type stated wherein novel means are presented for increasing the pressure applied to hydraulic fluid at any desired multiple of the line pressure of the air in the tractor brake system so that requisite forces provided for independently and reliably supporting the trailer together with its load.
It is another object of the present invention to provide a landing gear actuating system for tractor-trailer combinations which includes conveniently accessible, manually controllable valves for expeditious operation so that extension and retraction of the landing gear may be effected with minimum effort on the part of the user without requiring developed skill for operation thereof.
It is a still further object of the present invention to provide a landing gear system of the type stated which incorporates valve means conducing to efficient and rapid operation of the system as well as for assuring that complete safety of the system in any selected condition so that accidental, premature or unauthorized movement of the supporting leg, i.e., the landing gear, is prevented.
It is another object of the present invention to provide a landing gear system of the type stated including landing gear actuating cylinders wherein only hydraulic fluid is introduced and where air is not present in such cylinders which might cause corrosion, sticking, and the like.
It is another object of the present invention to provide a tractor-trailer landing gear system of the type stated wherein hydraulic fluid can be introduced into cylinders of the landing gear legs under high pressure for either extension or retraction purposes.
It is yet another object of the present invention to provide a tractor-trailer landing gear system of the type stated wherein the hydraulic landing gear actuating cylinders can be simultaneously or individually extended or retracted for leveling of a trailer.
It is a further object of the present invention to provide a tractor-trailer landing gear system of the type stated utilizing air from the airbrake system of the tractor but which makes efficient and effective use of such air to prevent wasting thereof or exhausting of the tractor air supply while ensuring proper operation of the system for hydraulic fluid pressure boosting purposes.
It is a still further object of the present invention to provide a tractor-trailer landing gear system of the type stated which is comprised of a minimum of parts; which is resistant to breakdowns; which can be easily provided upon existing truck equipment without requiring costly structural modification thereof; which is entirely automatic in operation; which obviates arduous physical effort by trucking personnel; which is economically produced; and which is durable in operation.
Other objects and details of the system will be in part apparent and in part pointed out hereinbelow.